The invention relates to an apparatus for controlling the bobbin drive of a flyer roving frame, the drive of which for the supply rolls and the flyers can be stepwise adjusted, during building the bobbin, to different rotational speeds. The drive contains an adjustable transmission system, which is coupled to a differential gear and which can be acted on by an adjusting element.
On flyer roving frames, the roving supplied by the delivery rolls of a drafting system is given a constant twist by means of a flyer, and a bobbin with conical ends is built from the twisted roving. To achieve this, it is usual to drive the supply rolls and flyers at a constant speed and at a fixed ratio to each other, and to drive the bobbins, which can be moved up and down and are mounted, for example, on a bobbin carriage, at a higher speed than the flyers, so that the bobbin leads the flyer. Corresponding to the increasing bobbin diameter, for orderly winding-up of the roving at a constant delivery speed firstly the bobbin lifting speed and secondly the bobbin lead relative to the flyer must decrease. The variable bobbin rotation speed is effected by an adjustable transmission system, for example, a cone gear, which can be acted on by an adjusting element, in connection with a differential gear. The circumstance that the tension of the roving on the bobbin increases with increasing bobbin diameter because of the increasing centrifugal forces is taken into account by having the flyers revolve, not at their highest possible speed, but at a speed of rotation which is from the beginning set lower, which corresponds to the centrifugal force at the full bobbin diameter, and which is constant during the whole building of the bobbin. This does in fact prevent roving breaks and thin places on the bobbin in the end phase of bobbin formation; however, these measures lead to a considerable loss of production.
It has therefore already been proposed to reduce the speed of the flyer and delivery roller during bobbin buildup, while maintaining the required speed ratio between the bobbin and flyer for an orderly windup (British Pat. No. 1,205,555). The proposal envisages starting from the highest possible flyer speed or, as the case may be, adjusting the programmed machine speed such that it begins below that speed which produces the maximum surface speed of the bobbin. This speed is kept constant until the bobbin reaches a diameter which corresponds to that which provides the maximum bobbin surface speed. From there onwards, there comes into action the switch element of a control gear directly following, and driven by, the drive motor, and automatically adjusts the machine speed in order to keep the bobbin surface speed constant at the maximum value. The switch element is actuated by a reciprocable rod which displaces the belt of a hyperbolic-cone cone gear and which itself is moved by a switch apparatus which is not further described since it is conventional. These conventional switch apparatuses or adjusting elements change the belt rod over in constant switching steps during the whole bobbin buildup, with a cone gear with hyperbolic cones.
With the change of the rotational speed of the flyer, however, the pressure of the presser finger and the frictional conditions in the flyer change, with the consequence that the layers of roving wound on the bobbin correspondingly change in thickness. It is thus not possible in practice to use constant switching steps for the adjusting gear or a constant switching angle for the adjusting element influencing the output rotational speed of the adjusting gear, during bobbin buildup, since in this case there arise different tensions of the roving between the supply roller and the bobbin. The operability of the known apparatus is thus not guaranteed.